Semiconductor light emitting device provided with a light conversion element using a haloborate phosphor composition

ABSTRACT

A light emitting device is provided that has a semiconductor light emitting element and a phosphor which converts a part of the luminescence spectrum emitted from the semiconductor light emitting element. The luminescence spectrum of the semiconductor light emitting element is located between a near ultraviolet region and a short-wavelength visible region, and the phosphor is made by adding a red luminescent activator to a base material of a blue luminescent phosphor. Thereby, improving the color shading generated by the dispersion of the spectra of the light emitting elements and obtaining the light emitting device having a high brightness and a good color rendering properties. With the light emitting device, it is possible to provide the light sources for the lighting apparatus of medical treatments, the flash plate of a copying machine, etc., in which a good color rendering property is required.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is related to a light emitting device having a lightemitting element and a phosphor, which can be used for various lightsources such as a signal light, lighting, a display, an indicator.Especially, the present invention provides the light emitting devicewhich can emit a white light by using the phosphor which is excited bythe emission spectrum from the light emitting element and capable ofemitting a visible light.

2. Description of the Related Art

Various light emitting diodes and laser diodes are developed as asemiconductor light emitting device today. Such a semiconductor lightemitting device has begun to substitute for an electric bulb and a coldcathode tube as various light sources, such as a display, a back lightand an indicator. These light sources use the strong points of alow-voltage drive, small sizing, lightweight, thin shape, highreliability with a long-life, low electrical power consumption.

Especially, the light emitting element using a nitride semiconductor hasbeen developed as a light emitting element which can emit a light in arange from the ultraviolet region to the short wavelength side ofvisible light. The blue or green LED of more than 10 candela has anactive (light emitting) layer of quantum well structure made of nitridesemiconductor (for example, mixed crystal of InGaN) and has beendeveloped and commercialized.

A display of mixed-color including white is realized by combination ofthe light from such a LED chip 1 and the light from the phosphor whichis excited by the emitted light. For example, such devices are mentionedin the JP,5-152609,A, JP,9-153645,A, JP,10-242513,A, etc.

More concretely, the light emitting element emits an ultraviolet lightor a blue light which has a relatively short wavelength in visiblelight. It is the light emitting diode which excites a phosphor in orderto emit the visible light having a wavelength longer than the wavelengthof the light emitting element. When a part of light from a lightemitting element is used as transmitted light, there are advantages suchthat the structure can be simplified and the output can be easilyimproved.

On the other hand, when a light emitting element which emits anultraviolet light is used, a white light is emitted by combining thephosphors which can emit RGB (red, green, blue) lights. In thisconfiguration, since the lights emitted from the phosphors are basicallyused only, a color adjustment can be performed comparatively easily.Especially, when a wavelength of the ultraviolet region is used, sincethe variations, such as wavelength of a semiconductor light emittingelement, are canceled and the chromaticity is determined by onlyluminescence colors of the phosphors, the productivity is improved ascompared with the case where the semiconductor light emitting elementwhich emits a visible light is used.

However, to utilize the light emitting device with the advantages ofsemiconductor light emitting elements as a light source such as alighting, current light emitting devices are not enough, so improvementin the brightness and improvement in the productivity are required.

Especially, the phosphors, which can be excited by the ultraviolet lightor the light of short wavelength in the visible range, and which canemit a red light with sufficient brightness as compared with other blue,green, etc., is not known. For this reason, the luminescent color madefrom the three primary colors only from phosphors has little redcomponent, so such a luminescent color is felt as a somber color sincethe red component is not reproduced. On the other hand, if mixed rate ofa red phosphor is raised to improve the color rendering property,relative luminance will fall.

If the excitation spectrum curve of the phosphor with respect to theluminescent spectrum of the light emitting element is variedsignificantly, although the luminescent spectrum emitted from the lightemitting element is positioned in a region of ultraviolet range orvisible range of which visual sensitivity is very small, the variationin a color tone may arise between the light emitting devices, becausethe slight variation of the excitation spectrum from the light emittingelement generate variation of the brightness of the phosphor.

Furthermore, when the excitation light spectral band width of a phosphoris narrow, the reliability of the light emitting device will be spoiledby the ultraviolet or near-ultraviolet light which is not absorbed bythe phosphor among the light emitted from the light emitting element. Iforganic materials are used for the package housing the light emittingelement, sealing member for protecting the light emitting element, thebinder member for the phosphor, the output power is depredated andluminescent color is shifted by coloring or degradation of the organicmaterials caused by the light which is not absorbed by the phosphor.

Moreover, in order to improve productivity, it is necessary to realizevarious desired colors by adjusting composition of one phosphor.

BRIEF SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a lightemitting device in which deterioration of output power and color shiftare extremely small and a color rendering properties are good.

The inventor accomplished the present invention based on following ideas(1) and (2) in the light emitting device having a light emitting elementand a phosphor.

(1) It is necessary to achieve the object that the light emittingelement has a luminescence spectrum in a range from near ultravioletregion to short-wavelength visible region so as to make the visualsensitivities of the variation of the luminescence spectrum emitted fromthe light emitting element extremely small.

(2) It is necessary to achieve the object that the phosphor is able toconvert at least a part of the luminescence spectrum of the lightemitting element and has an excitation spectrum curve which is notchanged significantly and which has a flat and wide portion near thepeak, and the phosphor can be adjusted so as to have various desiredchromaticness by adjusting the composition.

A light emitting device related to the present invention has asemiconductor light emitting element and a phosphor which converts apart of the luminescence spectrum emitted from the semiconductor lightemitting element. The light emitting device characterized in that thesemiconductor light emitting element has a luminescence spectrum locatedbetween a near ultraviolet region and a short-wavelength visible region,and the phosphor is made by adding a red luminescent activator to a basematerial of a blue luminescent phosphor.

The double activated phosphor which is used in the light emitting deviceof the invention and which is made by adding a red luminescent activatorto a base material of a blue luminescent phosphor has a stableexcitation spectrum curve with a little change in the vicinity of thewavelength where luminescence efficiency is high. Moreover, theexcitation spectrum has two or more peaks each of which has a broad halfband width. In the excitation spectrum curve, the parts between theadjacent peaks are nearly flat respectively. With this, since thephosphor can absorb a light with a wavelength of the ultraviolet regionwhich damages organic members and can convert to the light of longerwavelength, the light emitting devices which have a good reliability andsmall dispersion in color tones can be obtained. The changes from thepeaks in the excitation spectrum curve between the peaks are preferablyin a range from 0 arb. unit to 0.2 arb. unit, more preferably in a rangefrom 0 arb. unit to 0.1 arb. unit, most preferably in a range from 0arb. unit to 0.05 arb. unit. Moreover, the phosphor used in the presentinvention is made by adding a red luminescent activator which emits alight of longer wavelength to a base material of a blue luminescentphosphor which emits a light of shorter wavelength, and various desiredchromaticness can be realized by adjusting the added ratio of the redluminescent activator.

In the device of the present invention, the light emitting device ofsimple structure with good productivity can be constituted by settingthe main peak wavelength of the semiconductor light emitting element to360 nm or more in a range of the ultraviolet region.

An another aspect of the light emitting device according to the presentinvention has a semiconductor light emitting element and a phosphorcapable of converting a part of a luminescence spectrum emitted from thesemiconductor light emitting element. The light emitting device ischaracterized in that the luminescence spectrum of the semiconductorlight emitting element is located between a near ultraviolet region anda short-wavelength visible region, and the phosphor is an alkaline earthmetal boric halide phosphor including at least one element representedby M selected from the group consisting of Mg, Ca, Ba, and Sr and atleast one element represented by M′ selected from the group consistingof Mn, Fe, Cr, and Sn. With this, the light emitting device which iscapable of emitting a white light with high brightness and which has agood productivity can be obtained.

In the light emitting device of the present invention, it is preferablethat the light emitting layer of the semiconductor light emittingelement is made of a nitride semiconductor including at least In and Gaor a nitride semiconductor including at least Ga and Al. Because such asemiconductor light emitting element can emit a light in a regionranging from the long wavelength side of ultraviolet to the shortwavelength side of visible region and has a narrow luminescence spectrumwidth, the phosphor can be excited efficiently and the light emittingdevice can be emit a light of the luminescence spectrum of which colortone is not affected by the light emitting element. It is to beunderstood that these may include the nitride semiconductor having In,Al and Ga.

In the light emitting element of the present invention, the phosphor isan alkaline earth metal boric halide phosphor activated by at least Mnand Eu. The phosphor has a good light resistance and a good heatresistance and can absorb the luminescence spectrum emitted from thelight emitting element efficiently. It is possible to emit a light of awhite region and the region can be adjusted by the composition.Moreover, it is possible to absorb a light of the longer wavelength sideof ultraviolet region and to emit a light of yellow or red color withhigh brightness. Therefore, the light emitting device having a goodcolor rendering properties can be obtained. It is to be understood thatthe alkaline earth metal boric halide phosphor includes an alkalineearth metal boric-chlor phosphor.

In the light emitting element of the present invention, the phosphor maybe a phosphor represented by a formula of (M_(1-x-y)Eu_(x)M′_(y))₂B₅O₉M″(where M is at least one selected from the group consisting of Mg, Ca,Ba, sr and M′ is at least one selected from the group consisting of Mn,Fe, Cr and Sn, 0.0001≦x≦0.5, 0.0001≦y≦0.5, M″ is at least one halogenselected from the group consisting of F, Cl, Br and I). With this, thelight emitting device which is capable of emitting the mixed color lightand has a good productivity can be obtained.

An another aspect of the light emitting device according to the presentinvention includes a semiconductor light emitting element of whichluminescence spectrum is located between a near ultraviolet region and ashort-wavelength visible region, and a first phosphor which converts apart of a luminescence spectrum emitted from the semiconductor lightemitting element. The first phosphor is made by adding an activator forred light emission to a base material of a blue emitting phosphor. Thisanother aspect of the light emitting device is characterized that asecond phosphor which can convert a part of the light emitted from thefirst phosphor to a light having a wavelength in a region ranging fromblue region to red region is included, and a light which has awavelength within a range of white region is emitted by mixing of thelight emitted from the first phosphor and the light emitted from thesecond phosphor.

The light emitting device of the present invention may include aphosphor selected from the group consisting of;

an alkaline earth halogen apatite phosphor activated by Eu, or Eu and Mn[(Sr, Ca, Ba, Mg)₅(PO₄)₃(F, Cl, Br):Eu, Mn],

an alkaline earth metal aluminate phosphor [SrAl₂O₄:Eu, Sr₄Al₁₄O₂₅:Eu,Mn, CaAl₂O₄:Eu(Mn), BaMg₂Al₁₆O₂₇:Eu, BaMg₂Al₁₆O₂₇:Eu, Mn andBaMgAl₁₀O₁₇:Eu (Mn)],

an yttrium aluminate phosphor activated by cerium,

a rare earth acid sulfide phosphor activated by Eu (La₂O₂S:Eu, Y₂O₂S:Euand Gd₂O₂S:Eu),

an organic complex phosphor activated by Eu [(Sr, Ca, Ba,Mg)₅(PO₄)₃Cl:Eu, ZnS:Cu, Zn₂GeO₄:Mn, (Sr, Ca, Ba, Mg)Ga₂S₄:Eu, and (Sr,Ca, Ba, Mg)₂Si₅N₈:Eu. With this, the color tone can be adjusted indetail and a white light having good color rendering properties can beobtained with a relatively simple construction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example showing a luminescence spectrum emitted from thelight emitting device of the present invention.

FIG. 2A is a plan view showing a surface mounting type light emittingdevice of the present invention.

FIG. 2B is a schematic cross-sectional view showing a surface mountingtype light emitting device of the present invention.

FIG. 3 is CIE chromaticity diagram showing the chromaticity of thephosphor used in the light emitting device of the present invention.

FIG. 4A is a luminescence spectrum diagram of the phosphor excited bythe light having a wavelength of 400 nm in the Example 1.

FIG. 4B is a luminescence spectrum diagram of the phosphor excited bythe light having a wavelength of 400 nm in the Example 9.

FIG. 5A is an excitation spectrum of the phosphor at the emittingwavelength of 455 nm in the Example 1.

FIG. 5B is an excitation spectrum of the phosphor at the emittingwavelength of 455 nm in the Example 1.

FIG. 6A and FIG. 6B are examples of luminescence spectra of thesemiconductor light emitting elements used in the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 2, an embodiment of the present invention will bedescribed in detail. A surface mounting type light emitting device shownin FIG. 2 is formed. A nitride semiconductor light emitting elementcomprising InGaN semiconductor which has a light emitting layer havingan emission peak wavelength of about 400 nm as shown in FIG. 6B is usedas the light emitting element. More specifically, the light emittingelement has a structure in which an n-type GaN layer of undoped nitridesemiconductor, a GaN layer which is an n-type contact layer doped withSi to be formed with n-type electrode, an n-type GaN layer of undopednitride semiconductor, an n-type AlGaN layer of nitride semiconductorand a light emitting layer having a single quantum well structure ofInGaN layer are laminated on a sapphire substrate in order. An AlGaNlayer as a p-type cladding layer doped with Mg and a GaN layer which isa p-type contact layer doped with Mg are laminated on the light emittinglayer in order (A buffer layer of GaN grown at a low temperature isformed on the sapphire substrate. And the p-type semiconductor isannealed at 400° C. or more after growing.) The p-type contact layer andthe n-type contact layer are exposed by etching at the same side oflaminated nitride semiconductor layers on the sapphire substrate. Ann-electrode is formed on the exposed n-type contact layer in a stripshape and a transparent p-electrode of metal thin layer is formed onalmost entire surface of the remaining p-type contact layer. A padelectrode is formed on the transparent p-electrode in parallel with then-electrode by spattering method.

Next, the light emitting element chip 1 is mounted on an iron packagewhich has a thin portion and a thick portion. The package has a recessportion which is the thin portion at a central part and cover leadelectrodes 3 plated with Ni/Au are fixed integrally at the thick portionsurrounding the recess portion with an insulator 2 between them. Thebottom surface of the recess in the thin portion and the bottom surfacesof the lead electrodes 3 are arranged on a same plane and the both ofthem are designed so as to contact a print circuit board. The LED chip 1is die-bonded in the recess by an Ag—Sn alloy. With this, the heatgenerated by LED chip 1 during lighting is released efficiently to theprint circuit board side via the thin portion of bottom surface of therecess. The electrodes of LED chip 1 are electrically connected to themain surfaces of the lead electrodes respectively by Ag wires 4.

Next, a color conversion layer including an alkaline earth metalboric-chlor phosphor 8 activated by Eu and Mn of(Sr_(0.09)Eu_(0.05)Mn_(0.05))₂B₅O₉Cl and SiO₂ is formed continuously ona surface of the LED chip 1 and an inner wall of the recess by spraycoating method. Hereafter, a method for formation of the colorconversion layer will be described in detail.

Process 1.

Although an alkyl silicate, a methyl silicate, an ethyl silicate, anN-propyl silicate and an N-butyl silicate as an alkyl silicate may beused, Oligomer liquid of a condensed ethyl silicate having 40 weight %of SiO₂ is used in the embodiment. The ethyl silicate is used aftersolation by hydrolysis with water including a catalyst.

The ethyl silicate sol, ethylene glycol and the phosphor 8 are mixed atthe weight ratio of 1:1:1 and stirred to make a coating medium. Theethyl silicate sol tend to be dried easily, so the ethyl silicate solpreferably should be mixed with an organic solvent having a high boilingpoint (100° C.˜200° C.) such as butanol and ethylene glycol to preventfrom gelation. Thus, clogging of the nozzle caused by gelation of ethylsilicate sol can be prevented by mixing with the organic solvent havinga high boiling point, so that working efficiency can be improved.

Process 2.

The coating medium is poured into a container and is carried from thecontainer to the nozzle by using a circulating pump. A flow rate of thepaint is adjusted by a valve. It is characterized in that the atomizedcoating medium sprayed from the nozzle is atomized and applied with aspiral rotation. Concretely, the atomized coating medium spreads in coneshape near the nozzle and spreads in column shape as the distance fromthe nozzle increases. With this, since the color conversion layer, inwhich the phosphor 8 is dispersed uniformly, is formed on all of theupper surface, side surface and corner surface with a uniform thickness,the color shading can be reduced. The phosphor 8 in the color conversionlayer is preferably a single-particle layer in which the phosphorparticles are arranged laterally to improve an output efficiency. In thepresent embodiment, the distance between the top surface of the lightemitting element and the lower end of the nozzle is adjusted to 40-50 mmso that the surface of the light emitting element is placed in thecolumn shaped atomized coating medium, and the coating medium and gasare jetted to the upper face, the side faces, the corners of the lightemitting element and the plane in the recess. With this, the continuouscolor conversion layer having a substantially uniform thickness can beformed.

Moreover, the above-described process is carried out while warming theportion to be coated. Thus, ethanol and a solvent formed by the solationof ethyl silicate can be evaporated simultaneously with the spray on thelight emitting element. With this, the color conversion layer can beformed without damaging the light emitting element. Concretely, thecoating medium and gas are jetted to the upper face, side faces andcorners of the light emitting element and the plane in the recess forspray coating while placing the light emitting element on the heater.The temperature of the heater is preferably adjusted in a range from 50°C. to 300° C.

Process 3.

Next, the phosphor 8 is fixed with SiO₂ by reaction of ethyl silicatesol and the water in the air at the room temperature (25° C.).

Process 4.

Next, drying at 300° C. for two hours is carried out. The performance ofthe light emitting element deteriorates under a temperature higher than350° C. Therefore, an alkyl silicate which can fix to the surface of thelight emitting element at 300° C. or less is used preferably as a fixingagent.

After the moisture in the recess of the package coated with the phosphor8 is thoroughly removed, it is sealed with a cover lid having a glasswindow at a center thereof by way of seam welding. In the presentembodiment, the phosphor 8 is fixed in the vicinity of the LED chip.However, the phosphor 8 may be applied on the rear surface or the mainface of the light extract portion. With this, the distance between thelight emitting element and the phosphor 8 can be kept even and a highreliability can be maintained even if the phosphor 8 is relatively weekto heat.

The light emitting device made by aforementioned method can emit a whitelight with high intensity. The luminescence spectrum of the lightemitting device is shown in FIG. 1. The light emitting device in whichchromaticity can be adjusted easily and which has a good productivityand a high reliability can be made. Each component of the presentinvention is described in detail.

<Light Emitting Element 1>

In the present invention, the light emitting element 1 has a lightemitting layer which can emit the light capable of exciting the phosphor8. Various semiconductors such as ZnSe and GaN can be given as thematerial of such semiconductor light emitting element. The nitridesemiconductor (In_(X)Al_(Y)Ga_(1-X-Y)N, 0≦X, 0≦Y, X+Y≦1) which can emita light with short wavelength capable of exciting the phosphor 8efficiently is more preferably given. The nitride semiconductors maycontain Boron and/or Phosphorus arbitrarily. A homojunction structure, aheterojunction structure or a double heterojunction structure which haveMIS junction, PIN junction or PN junction are given as a semiconductorstructure. The luminescence wave length can be variously selected by thematerial of semiconductor layers and mix crystal ratio thereof. Theactive layer may have a single quantum well structure or a multiplequantum well structure in which a semiconductor active layer is formedto be a thin film which generates quantum effect. When the nitridesemiconductor is used, materials such as sapphire, spinel, SiC, Si, ZnOand GaN are preferably used as a substrate for the semiconductor. Thesapphire substrate is preferably used for forming the nitridesemiconductor having good crystallinity in mass production. The nitridesemiconductor can be formed on the sapphire substrate using the MOCVDmethod and the like. A buffer layer made of material such as GaN, AlNand GaAlN is grown on the sapphire substrate, and then the nitridesemiconductor having a p-n junction is formed on the buffer layer.

As an example of the light emitting element which has a p-n junctionusing the nitride semiconductor, a light emitting element having adouble hetero-structure in which a first contact layer of n-type galliumnitride, a first clad layer of n-type Aluminum gallium nitride, anactive layer of Indium gallium nitride, a second clad layer of p-typeAluminum gallium nitride, and a second contact layer of p-type galliumnitride are laminated in order on the buffer layer is given.

The nitride semiconductor exhibits n-type electro conductivity in acondition where an impurity is not doped. It is preferable toappropriately introduce the n-type dopant such as Si, Ge, Se, Te and Cfor forming a desired n-type nitride semiconductor, for example, inorder to improve luminous efficiency. On the other hand, when p-typenitride semiconductor is formed, it is preferable that the p-type dopantsuch as Zn, Mg, Be, Ca, Sr and Ba is doped. The nitride semiconductor ishardly made to be the p-type by simply doping with the p-type dopant.Therefore, it is preferable to make it low resistance by heating in afurnace, or plasma irradiation and the like after the p-type dopant isintroduced. The light emitting element 1 comprising the nitridesemiconductor is prepared by cutting the semiconductor wafer into chipsafter electrodes have been formed.

In the present invention, a color conversion type light emitting devicewith a small color tone shading can be made by the combination of alight emitting element having a main emission wavelength in a regionfrom the near ultraviolet to the short-wavelength visible region and thephosphor 8 which absorbs a part of the light emitted from the lightemitting element and capable of emitting the light having a differentwavelength from the light emitting element. Here, it is preferable touse a resin which is relatively resistant to ultraviolet light or aglass which is an inorganic material substance.

<Metal Package 5>

In the embodiment of the present invention, the metal package 5 has athin recess portion for housing the light emitting element and a thickportion where the lead electrodes 3 are provided. The bottom surface ofthe recess portion and the bottom surfaces of the lead electrodes 3 arealmost positioned on a same plane.

The metal package 5 is preferably made of the thin plate inconsideration of small sizing and the efficient radiation of the heatgenerated by the light emitting element 1. On the other hand, thecontact area between the metal of the package and the insulating member2 adjacent to the metal need to be larger in order to improve thereliability of the device by reducing the difference in thermalexpansion between the metal package and the insulating member 2 adjacentto the metal, so that the metal package 5 is preferably formed with athick wall. Therefore, in the present invention, the metal packagehaving the thin portion for housing the light emitting element and thethick portion for fixing the lead electrodes 3 is used, so that thelight emitting device having a good reliability is provided.

(Phosphor 8)

The phosphor 8 used in the light emitting device of the presentinvention can emit efficiently by the luminescence spectrum of the lightemitting element. The phosphor 8 preferably has an excitation region atleast in the ultraviolet region. The phosphor 8 absorbs at least a partof light having a main luminescence wavelength longer than 360 nm in theultraviolet region and is made by adding a red luminescent activator toa base material of a blue luminescent phosphor. The phosphor of analkaline earth metal boric halide phosphor in which at least Mn which isa red luminescent activator is included in a base material of a blueluminescent phosphor activated by Eu is given as an example of thephosphor 8.

The phosphor 8 can be made by the following method. The oxides of theelements of the phosphor 8 or compounds which can be transformed tooxides by thermal decomposition and ammonium chloride are weighed aspredetermined amounts and mixed by a ball mil. The mixture is placed ina crucible and is fired in a reducing atmosphere of N₂, H₂ at 500°C.-1000° C. for 3-7 hours. The fired product is wet milled, sieved,dehydrated, and dried, thereby obtaining the powder of the alkalineearth metal boric halide phosphor.

In the alkaline earth metal boric halide phosphor of(M_(1-x-y)Eu_(x)M′_(y))₂B₅O₉M″ (where M is at least one selected fromthe group consisting of Mg, Ca, Ba, Sr, M′ is a red luminescentactivator and is at least one selected from the group consisting of Mn,Fe, Cr, Sn, 0.0001≦x≦0.5, 0.0001≦y≦0.5, and M″ is at least one halogenselected from the group consisting of F, Cl, Br, I), x which is thecomposition ratio of the first activator Eu is preferably set in a rangeof 0.0001≦x≦0.5, since the luminescent brightness tends to lower when xis less than 0.0001 and the luminescent brightness tends to lower byconcentration quenching when x is more than 0.5. The value of x is morepreferably in a range of 0.005≦x≦0.4, most preferably in a range of0.01≦x≦0.2. The value of y which is a composition ratio of at least oneelement of Mn, Fe, Cr, Sn is preferably set in a range of 0.0001≦y≦0.5,more preferably in a range of 0.005≦y≦0.4, most preferably in a range of0.01≦y≦0.3. The luminescent brightness is lowered by concentrationquenching, when y is more than 0.5.

The phosphor 8 can show a luminescent color in a range of blue-white(for example, White in trivial color based on Japanese IndustrialStandard (JIS) Z8110, or base white in the system color namediagram)-red by a excitation light in a range from the ultraviolet torelatively short wavelength side of the visible region (for example, themain wavelength of less than 440 nm).

A general color rendering index Ra more than 90 can be obtained, sinceit can emit with high brightness efficiently by a short wavelengthvisible light or an ultraviolet light having a main wavelength of therelatively longer wavelength as shown in FIGS. 6A and 6B and redcomponent is included sufficiently.

FIG. 3 is a CIE chromaticity diagram showing the luminescent colorexamples excited by 365.0 nm in the phosphors 8 used in the Examples 1to 4 of the present invention. The diagram shows that the luminescentcolor of the light emitting device can be changed in a range ofblue-white-red and the color tone can be adjusted by changing thecomposition ratio of the phosphor 8.

Although, when M is Sr, the phosphor emits a light of which luminescentcolor is blue by the luminescence of Eu²⁺ having a peak in the vicinityof 450 nm, the luminescent color of the phosphor 8 shows a luminescentcolor in a range of blue-white-red by the red luminescence of Mn byincreasing the value y in Mn of M′. When M is Ca, the change is the samewith regard to the amount of Eu and Mn. However, when M is Ba, changingof the luminescent color is small.

FIG. 4A shows the luminescence spectrum of the phosphor 8 of Example 1under the 400 nm excitation and FIG. 5A shows the excitation spectrum ofthe phosphor 8 of Example 1 in relation to the 455 nm emission. Thesimilar excitation spectrum is obtained even in the case of theexcitation by a 590 nm emission. The figures show that the phosphor 8used in the present invention is excited efficiently by a light in arange from the longer side wavelength ultraviolet light to the shorterside wavelength (for example, from 250 nm to 425 nm) visible light andthe luminescent color is included in the region of base white of JISZ8110. Since the phosphor 8 is excited efficiently by any ultravioletlight, the phosphor 8 is expected to be effectively used for a shortwavelength side ultraviolet light.

FIG. 4B shows the luminescence spectrum of the phosphor 8 of Example 9under the 400 nm excitation and FIG. 5B shows the excitation spectrum ofthe phosphor 8 of Example 9 in relation to 455 nm emission. The similarexcitation spectrum is obtained even in the case of the excitation by590 nm emission.

Furthermore, the phosphor 8 used in the light emitting device of thepresent invention may include an element selected from Tb, Cu, Ag, Au,Cr, Nd, Dy, Co, Ni, Ti and Pr with Eu according to need.

In the light emitting device of the present invention, a second phosphorhaving a luminescence spectrum different from the both spectra of thelight emitting element and the first phosphor may be used in addition tothe first phosphor which can be excited by at least an ultraviolet lightemitted from the light emitting element and which is made by adding ared luminescent activator to the base material of a blue luminescentphosphor. The excitation source of the second phosphor may be the lightemitting element or the first phosphor, or both of the light emittingelement and the first phosphor. The second phosphor preferably emits alight between the blue region and the red region to provide the lightemitting device capable of emitting the various kinds of neutral color.

The first phosphor and the second phosphor may be composed of one kind,or two or more kinds respectively. With this, since the combinations ofthe luminescent spectra enlarges infinitely, the light emitting devicehaving a good color rendering property and high brightness can beobtained. In addition, when they are in relation of complementary color,a white light can be emitted efficiently. When the second phosphor isexcited by the first phosphor and the first phosphor is composed of twoor more kinds, it is not necessary that the all kinds of the firstphosphor are excitation sources, the second phosphor may be excited byany of the first phosphor. When the first and the second phosphors arecomposed of not only one kind but also two or more kinds respectively,the first and the second phosphors can be made in relation ofcomplementary color. With this, the light emitting device having a goodcolor rendering property can be made. The color shading is improved ascompared with the case that only one of the first and second phosphorsis composed of two or more kinds and the complementary color isrealized. For example, when the first phosphor is composed of two kindsand they are in relation of complimentary color, the total color tone isvaried with time by losing the balance of the color tones by such as athermal degradation of any of the phosphors. When the second phosphor iscomposed of two or more kinds and they are in relation of complimentarycolor, the total color tone is varied similarly.

Sapphire(aluminum oxide) phosphor activated by Eu and/or Cr,CaO—Al₂O₃—SiO₂ phosphor having nitrogen activated by Eu and/or Cr(oxynitride phosphor glass), and M_(x)Si_(y)N_(z):Eu (where M is atleast one element selected from the group consisting of Mg, Ca, Ba, Srand Zn, z=⅔x+ 4/3y), which are phosphors that absorb a light in a rangeof blue-blue green-green and can emit a red light, are given forExamples of the second phosphor. With this, the luminescence having muchred component and a good color rendering property can be obtained by themixed color of the light emitted from the first phosphor and the lightemitted from the second phosphor excited by the first phosphor. Such awhite light having a good color rendering property preferably may beused for the lights of medical facilities, the flash lamps of copyingmachines and the like.

Yttrium aluminum oxide photoluminescence phosphors activated by Ce whichare represented by the formula of (Y_(z)Gd_(1-z))₃Al₅O₁₂:Ce(0<z≦1) andthe formula of (Re_(1-a)Sm_(a))₃Re′₅O₁₂:Ce(0≦a≦1, 0≦b≦1, Re is at leastone element selected from the group consisting of Y, Gd, La and Sc, Re′is at least one element selected from the group consisting of Al, Ga andIn), which absorb a light of blue-blue green-green and can emit a yellowlight are given as other Examples of the second phosphor. Since thephosphors contain Gd (gadolinium) in the crystal, the excitationluminescence efficiency in the longer wavelength region more than 460 nmcan be increased. The emission peak wavelength shifts to a longerwavelength with increasing the content of Gd. That is to say, aluminescent color having a large amount of red component can be obtainedby increasing the amount of the substitution of Gd. Furthermore, Tb, Cu,Ag, Au, Fe, Cr, Nd, Dy, Co, Ni, Ti, Eu and Pr may be contained inaddition to Ce if necessary.

In addition, the emission wavelength can be shifted to shorterwavelength side by substituting a part of Al by Ga in the composition ofYttrium aluminum garnet phosphor. Also the emission wavelength can beshifted to longer wavelength side by substituting a part of Y by Gd.When a part of Y is substituted by Gd, the substitution by Gd ispreferably less than 10 percent and the content (substitution) ratio ofCe is preferably set in a range of 0.03 to 1.0. While a green componentincreases and a red component decreases in case that the substitution byGd is less than 20 percent, the red component can be compensated byincreasing the content of Ce and the desired color tone can be obtainedwithout decreasing the brightness. With this composition, thetemperature characteristic is improved and the reliability of the lightemitting diode is improved. The light emitting device which can emit aneutral color light such as a pink can be obtained by using the photoluminescent phosphor adjusted so as to include much red component.

Such photo luminescent phosphors can be made by the following steps. Asraw materials of Y, Gd, Al and Ce, the oxides or compounds which caneasily transform to oxides at high temperature are prepared and mixedaccording to the stoichiometry to obtain the raw material. Alternately,the mixed raw material is made by mixing a coprecipitated oxide withaluminum oxide. The coprecipitated oxide is obtained by coprecipitatingthe solution made by solving the rare earth elements of Y, Gd and Ce inacid according to the stoichiometry with oxalic acid and firing. Thisraw material is mixed with fluoride such as barium fluoride and ammoniumfluoride in moderation, placed in a crucible and fired at 1350-1450° C.for 2-5 hours. And then the fired product is wet crushed by ball mil,washed, separated, dried and sieved to obtain the photo luminescentphosphor.

In the light emitting device of the present invention, at least onephosphor selected from the group of;

an alkaline earth halogen apatite phosphor activated by Eu, or Eu andMn((Sr, Ca, Ba, Mg)₅(PO₄)₃(F, Cl, Br):Eu, Mn),

an alkaline earth metal aluminate phosphor(SrAl₂O₄:Eu, Sr₄Al₁₄O₂₅:Eu Mn,CaAl₂O₄:Eu (Mn), BaMg₂Al₁₆O₂₇:Eu, BaMg₂Al₁₆O₂₇:Eu,Mn, andBaMgAl₁₀O₁₇:Eu(Mn)),

nitrogen-containing CaO—Al₂O₃—SiO₂ phosphor activated by Eu and/or Cr(oxynitride phosphor glass),

M_(x)Si_(y)N_(z):Eu (where M is at least one selected from Mg, Ca, Ba,Sr and Zn, z=⅔x+ 4/3y),

a rare earth acid sulfide phosphor activated by Eu (La₂O₂S:Eu, Y₂O₂S:Eu,and Gd₂O₂S:Eu),

an organic complex phosphor activated by Eu ((Sr, Ca, Ba,Mg)₅(PO₄)₃Cl:Eu, ZnS:Cu, Zn₂GeO₄:Mn, (Sr, Ca, Ba, Mg)Ga₂S₄:Eu, and (Sr,Ca, Ba, Mg)₂Si₅N:Eu may be used together with said photo luminescentphosphor. With this, the various desired luminescent colors can beobtained easily.

In the light emitting device of the present invention, when the pluralphosphors are used, the phosphors mixed evenly may be arranged or thephosphors may be arranged so as to be laminated at every phosphor.

The particle size of the phosphor is preferably in a range of 1 μm-100μm, more preferably in a range of 5 μm-50 μm, further preferably in arange of 10 μm-30 μm. The phosphor having a particle size less than 15μm tend to cohere easily. The phosphor has a high absorption ratio and ahigh conversion efficiency of light and a broad excitation wavelengthwidth by a particle size range. As described above, the light around themain wavelength of the light emitting element can be convertedefficiently and can emit by including such large size phosphor particleshaving good optical properties. Therefore, the productivity of the lightemitting device can be improved.

Here the particle size is a value obtained by a volume based particlesize distribution curve. The volume based particle size distributioncurve is obtained by measuring the particle size distribution by a laserdiffraction-scattering method. Specifically, the volume based particlesize distribution curve can be measured in a particle size range of 0.03μm to 700 μm by dispersing each material in a sodium hexametaphosphateaqueous solution of 0.05% concentration under environments of 25° C. andhumidity of 70%, using the laser diffraction type particle sizedistribution measuring apparatus (SALD-2000A). The median particlediameter is a particle size value at the integrated value of 50% in thevolume based particle size distribution curve and the median particlediameter of the phosphor used in the present invention is preferably ina range of 15 μm-50 μm so as to obtain a high brightness. The phosphorparticles having this median particle diameter are preferably containedwith high frequency and the frequency value is preferably in a range of20%-50%. Such phosphor particles having a small dispersion make itpossible to provide the light emitting device having a restrained colorshading and a good color tone.

The phosphor may be disposed at the various positions with relation tothe position of the light emitting element. That is to say, the phosphormay be disposed directly on the emission surface of the light emittingelement and may also be included in the die-bonding member fordie-bonding the light emitting element on the package or in the moldmember covering the light emitting element, and may be applied on thesurfaces of the package or a lid which is a sealing member. As describedabove, the phosphor is applied to the light emitting element directly orindirectly.

In the light emitting device of the present invention, the phosphor canbe adhered with various binders such as a resin which is an organicmaterial and glass which is inorganic material.

When an organic material is used as a binder, transparent resins whichare superior in antiweatherability, such as an epoxy resin, acryl resin,silicone resin, are preferably used. Especially, the silicone resin ispreferably used, since the silicone resin improves a good dispersibilityof the phosphor and has a good reliability. When an elastomeric orgelatinous member is used, the light emitting device having a highresistance against the thermal stress can be obtained.

An inorganic material may be used as a binder. The sedimentation methodor the sol-gel method may be used as an actual example. For example, aphosphor, silanol (Si(OEt)₃OH) and ethanol are mixed to make a slurry.The slurry is jetted from the nozzle and then the slurry is heated at300° C. for three hours to transform the silanol to SiO₂. With this, thephosphor is fixed at the desired place. Especially, when the phosphor isfixed on the window 7 of the lid, the inorganic material of whichthermal extension ratio is similar to the window 7 is preferably used,since the phosphor can be adhered to the window firmly.

A binding agent of inorganic material may be used as a binder. The bondis a so-called low melting point glass. The low melting point glass ispreferably fine particles and preferably has a small absorptivity to theradiation in a range from the ultraviolet region to the visible regionand extremely stable in the binder. The alkaline earth borate fineparticles made by sedimentation method are suitable for the particles.

When large sized phosphor particles are used, even if it has a highmelting point, the binding agent of ultra-fine particles such as asilica, an alumina, a pyrophosphate and an orthophosphate of an alkalineearth metal made by sedimentation method is preferably used. Thesebinding agents may be used individually or in combination.

Here, a coating method of the binding agent is described.

To heighten bonding effect, the slurry of the bond made by crushing thebonding material in a vehicle in wet is preferably used.

The vehicle is a high viscous solution made by solving a small amount ofa binding material in an organic solvent or deionized water. Forexample, an organic vehicle can be made by solving 1 wt % ofnitrocellulose in an organic solvent of butyl acetate.

The coating medium is made by adding the phosphor to the binding agentslurry. In the coating medium, an addition ratio of slurry may be set sothat the amount of the bond in the slurry is about 1-3 wt % with respectto the phosphor. To prevent from lowering the luminous flux maintenancefactor, the additional amount of the binding agent is preferablyreduced. The coating medium is applied on the rear surface of thewindow. Then, the coating medium is dried by flowing of warm air or hotair. Finally, the vehicle is vaporized by baking at 400° C.-700° C. Withthis, the phosphor layer is fixed by the binding agent on the desiredposition.

<Dispersing Agent>

In the present invention, the color conversion member may include adispersing agent together with the phosphor material. Barium titanate,Titanium oxide, Aluminum oxide, Silicon dioxide and soft or heavycalcium carbonate are preferably used as a dispersing agent. With this,the light emitting device having a desired directional pattern can beobtained.

In the present specification, the dispersing agents are particles havinga center particle size of 1 nm or more but less than 5 μm. Thedispersing agents having a center particle size of 1 μm or more but lessthan 5 μm reflect diffusely the light from the light emitting elementand the phosphor efficiently and can control an irregular color causedby using large size phosphor particles. The half-width of theluminescent spectrum can be reduced and the light emitting device havinga good color purity can be obtained. The dispersing agent of 1 nm ormore but less than 1 μm has a high transparency and can enhance aviscosity of resin without decreasing the luminosity by hightransparency, while the interference effect to the light wavelength ofthe light emitting element is small. When the color conversion materialis disposed by potting etc., since the phosphor is dispersed almostuniformly in the resin in the syringe and can maintain that state, it ispossible to produce with a good process yield even if the large sizedphosphor particles which are hard to handle are used. As describedabove, the dispersing agents have different rolls corresponding to theparticle size ranges respectively, so the dispersing agents can be usedby selecting or combining according to the usage.

<Filler>

In the present invention, fillers may be included in the colorconversion layer. The filler is similar to the dispersing agents inmaterial and different from the dispersing agents in median particlediameter. In the specification, the fillers are particles of whichcenter particle size is in a range of 5 μm-100 μm. When such particlesized fillers are included in the transparent resin, not only thechromaticity variation of the light emitting device is improved, butalso a resistance for thermal shock can be improved. Therefore, thelight emitting device having a good reliability prevented from breakingthe wire and from exfoliating the light emitting element from the bottomof the recess can be obtained. Moreover, it is possible to maintain aneven flowability of the resin for a long time and to form the sealingmember in desired position, and thereby making it possible to producewith a good process yield.

The fillers preferably have a particle size and/or a shape similar tothe phosphor particles. In the present invention, similar particle sizesmean that the difference between those center particle sizes is lessthan 20%. The similar shapes mean that the difference betweencircularity which is a degree of approximation to the perfect circle isless than 20% (The “circularity” is defined as the length of thecircumference of the perfect circle having an area equal to theprojected area of the particle/the length of the circumference of theprojection of the particle”). When such fillers are used, the phosphorand the fillers interact with one another and the phosphor particles canbe well dispersed in the resin, and thereby control an irregular color.Moreover, the phosphor and the fillers preferably have particle sizes ina range of 15 μm-50 μm, more preferably in a range of 20 μm-50 μm. Bythis particle size, the particles can be arranged with desired distancesbetween the particles. With this, the routes for outputting the lightcan be secured sufficiently, so the directional pattern can be improvedwithout decreasing the luminous intensity.

The invention will be understood in detail with reference to thefollowing examples. However, these examples are not to be construed tolimit the scope of the invention.

EXAMPLE 1

The light emitting device of surface mounting type shown in FIG. 2 ismade. The LED chip 1 is a nitride semiconductor element having a lightemitting layer made of InAlGaN semiconductor of which peak wavelength is400 nm of ultraviolet light.

More concretely, the LED chip 1 can be formed by depositing the nitridesemiconductors on a washed sapphire substrate by MOCVD method usingTMG(trimethyl-gallium) gas, TMI(trimethyl-indium) gas, nitrogen gas anddopant gas together with carrier gas. A layer to be the n-type nitridesemiconductor and A layer to be the p-type nitride semiconductor can bemade by changing between SiH₄ and Cp₂Mg as a dopant gas.

The LED chip 1 has an element structure constituted by laminating ann-type GaN layer of undoped nitride semiconductor, an Si doped GaN layerwhich is an n-type contact layer to be formed with an n-type electrode,an n-type GaN layer of undoped nitride semiconductor, an AlGaN layerincluding Si which is an n-type cladding layer and a light emittinglayer in order on a sapphire substrate. The light emitting layer has amultiple quantum well structure made by laminating five sets each ofwhich is composed of an AlInGaN layer to be a well layer and an AlInGaNlayer to be a barrier layer including Al more than the well layer. AMg-doped AlGaN layer for a p-type cladding layer, a GaN layer forimproving the electrostatic discharge tolerance and a Mg-doped GaN layerfor a p-type contact layer are laminated in order on the light emittinglayer. (A buffer layer of GaN grown at a lower temperature is formed onthe sapphire substrate. And p-type semiconductors are annealed at 400°C. or more after growth.)

In detail, after a buffer layer of GaN is grown at a thickness of 200 Åat 500° C. on a 2 inches diameter sapphire substrate having a main planeof a (0001) C plane, a temperature is risen to 1050° C. and then anundoped GaN layer is grown at a thickness of 5 μm. Although thethickness is not limited at 5 μm, it is preferable that the thickness ismore than the thickness of the buffer layer and not exceeding 10 μm.Next, after growing the undoped GaN layer, the wafer is taken out fromthe reactor. Then, stripe shaped photo masks are formed on the surfaceof the undoped GaN layer and masks of SiO₂ having 15 μm stripe widthsare formed at 5 μm intervals (window portions) at 0.1 μm thickness by aCVD apparatus. After the masks are formed, the wafer is taken in thereactor again and an undoped GaN layer is grown at 1050° C. at 10 μmthickness. Although, the crystal defect density of the undoped GaN layeris more than 10¹⁰/cm² or more, the crystal defect density of the GaNlayer is more than 10⁶/cm² or more.

Next, the n-type contact layer and n-type Gallium nitride compoundsemiconductor layer are formed. First, the n-type contact layer dopedwith Si at 4.5×10¹⁸/cm³ is grown at 1050° C. at the thickness of 2.25 μmusing source gases of TMG, ammonia gas, silane gas for impurity gas.Next, only the silane gas is stopped and the undoped GaN layer is grownat the thickness of 75 Å using TMG and ammonia gas. Successively, thesilane gas is flowed again and the GaN layer doped with Si at4.5×10¹⁸/cm³ is grown at the same temperature at the thickness of 25 Å.With this, a pair of A layer of the undoped GaN layer of 75 Å thicknessand B layer of the GaN layer doped with Si of 25 Å thickness is grown.The n-type Gallium nitride compound semiconductor layer of multilayerfilm having a super lattice structure is grown at 2500 Å thickness bylaminating the pairs 25 times.

Next, a barrier layer of undoped GaN is grown at 250 Å thickness.Successively, after the temperature is changed to 800° C., a well layerof undoped InGaN is grown at 30 Å thickness using TMG, TMI, ammonia. Theactive layer having a multiple quantum well structure and the totalthickness of 1930 Å is grown by laminating seven barrier layers and sixwell layers alternately in order of Barrier+Well+Barrier+Well+ . . .+Barrier.

Next, the p-type layers including a p-side multilayer film claddinglayer and p-type contact layer are formed. First, a third nitridesemiconductor layer of p-type Al_(0.2)Ga_(0.8)N doped with Mg at1×10²⁰/cm³ is grown at 1050° C. at the thickness of 40 Å using TMG, TMI,ammonia, Cp₂Mg(cyclopentadienyl magnesium). Successively, thetemperature is set at 800° C. and then a fourth nitride semiconductorlayer of In_(0.03)Ga_(0.97)N doped with Mg at 1×10²⁰/cm³ is grown at thethickness of 25 Å using TMG, TMI, ammonia, Cp₂Mg. The five third nitridesemiconductor layers and the five fourth nitride semiconductor layersare laminated alternately by repeating these growth processes andfinally the third nitride semiconductor layer is grown at the thicknessof 40 Å. With this, a p-side multilayer film cladding layer which is amultilayer film of super lattice structure having a total thickness of365 Å is grown. Next, the p-side contact layer of p-type GaN doped withMg at 1×10²⁰/cm³ is grown at 1050° C. at the thickness of 700 Å usingTMG, ammonia, Cp₂Mg.

After reaction, the temperature is lowered to the room temperature andthen the wafer is annealed in the reactor at 700° C. at a nitrideatmosphere, thereby furthermore lowering the resistances of the p-typelayers.

Next, the surfaces of the p and n-contact layers are exposed on a sameside of the sapphire substrate by etching. Concretely, the wafer istaken out from the reactor and then a mask is formed on the surface in apredetermined shape. Next, the surface of the n-type contact layer isexposed by etching from the p-type gallium nitride compoundsemiconductor layer side using an RIE (reactive ion etching) apparatus.

Each of the anode and cathode pad electrodes is formed on the surface ofeach contact layer by sputtering respectively. After a metal thin filmis formed on the all of the surface of the p-type nitride semiconductoras a transparent electrode, the pad electrode is formed on the part ofthe transparent electrode. Concretely, after etching, the transparentp-electrode (Ni/Au=60 Å/50 Å) having a 110 Å thickness is formed so asto cover nearly all surface of the p-type layer and then the padelectrode having three extended conducting line parts is formed with Auat 0.5 μm thickness along with an edge of a corner of the light emittingdevice on the transparent p-type electrode. On the other hand, ann-electrode including W and Al is formed opposite to the pad electrodeon the surface of n-contact layer exposed by etching. The preparedsemiconductor wafer is scribed and is divided by an external force,thereby forming LED chips 1.

On the other hand, Iron package 5 is used as a case of the lightemitting device. The iron package 5 has a thin portion in recess shapeat the center thereof and a thick portion elongated from the thinportion to edge and the thick portion has lead electrode pins 3penetrated in the through holes formed at the thick portion so as to besealed and insulated by glass 2. The iron package has support parts 14at the positions symmetric to the lead electrode pins with the recessbetween them of the bottom surface side. The support parts can be easilyformed by pressing on the side of the main surface of the iron package.With this, the stability of the package is improved, so a good opticalproperty can be obtained. The surfaces of the lead electrode pins 3 areplated with Ni/Ag layer.

The LED chip 1 is die-bonded with Ag—Sn alloy in the recess of thepackage constituted as described above. Next, each electrode of thedie-bonded LED chip 1 and each electrode pin 3 exposed on the bottomsurface of the recess of the package are electrically bonded with Agwire 4.

SrCO₃, H₃BO₃, Eu₂O₃, MnCO₃ and NH₄Cl are used as raw materials of thephosphor, they are weighed in the ratio according to the composition of(Sr_(0.90),Eu_(0.05),Mn_(0.05))₂B₅O₉Cl and Mixed. Where, content ofNH4Cl is preferably set twice as large as the composition (SrCO₃:265.7g, H₃BO₃:309.1 g, Eu₂O₃:17.6 g, MnCO₃:11.5 gNH₄Cl:106.9 g).

The weighed raw materials are fully mixed in dry by a mixing machinesuch as a ball mil. The mixed raw materials are filled in a crucible ofsuch as SiC, quartz or alumina and then the temperature is raised to1000° C. at the rate of 500° C./hour and maintained at the constanttemperature stage of 1000° C. for three hours in the reduced atmosphereof N₂, H₂. The fired product is wet crushed, dispersed, sieved,separated, washed, and dried, thereby obtaining the phosphor 8.

A solution made by mixing the obtained phosphor 8, an ethyl silicate soland ethylene glycol in the ratio of 1:1:1 by weight is agitated to beadjusted, thereby obtaining a coating medium and the coating medium isspray-coated on the surface of the LED chip 1 and inner wall of therecess of the package 5, while setting the package 5 provided with theLED chip 1 on a heater set at 200° C. The color conversion layer isformed by heat drying at 300° C. for three hours after once left at theroom temperature.

Next, the moisture content is exhausted fully from the recess and thenthe recess is sealed with the cover lid 6 having a glass window 7 at thecenter thereof by seam welding. The light emitting device composed asdescribed above has a good heat release characteristic and a high lightresistance to near ultraviolet and ultraviolet light, since all of theparts of the light emitting device are made of inorganic materials.

The chromaticity coordinates of the light emitting device can be made(x,y)=(0.329, 0.271). The luminescent efficiency is 25.2 m/W at thedriving condition of 20 mA. In the light emitting device by 400 nmexcitation according to Example 2, the luminescent brightness is 217%when the luminescent brightness of the light emitting device ofcomparative sample 1 is regarded as 100%. In the light emitting devicehaving the light emitting element which emits the excitation light of365 nm, the chromaticity coordinate (x,y)=(0.330,0.272) can be obtainedand the luminescent brightness is about 147%.

COMPARATIVE EXAMPLE 1

The light emitting device of Comparative sample 1 is made similar toExample 1 except that a phosphor which is made by mixing BaMg₂Al₁₆O₂₇:Euof a blue luminescence color, BaMg₂Al₁₆O₂₇:Eu, Mn of a greenluminescence color and Y₂O₂S:Eu of a red luminescence color so as tohave the chromaticity equal to Example 1 to obtain the same chromaticityis used instead of all of the phosphor of the present invention.

EXAMPLE 2

The light emitting device is made similar to Example 1 except that theraw materials of SrCO₃, MnCO₃ and Eu₂O₃ are adjusted and mixed accordingto the composition ratio (Sr_(0.94), Eu_(0.05),Mn_(0.01))₂B₅O₉Cl bychanging the ratio in the phosphor of Example 1, thereby obtaining thecolor tone of the chromaticity coordinates (x,y)=(0.210,0.103).Moreover, the luminous efficiency is 23.9 lm/W at the drive condition of20 mA. If the luminescent brightness of comparative example 1 isregarded as 100%, the luminescent brightness is about 206% in the lightemitting device excited by 400 nm according to Example 2. In the lightemitting device excited by 365 nm, the chromaticity coordinates(x,y)=(0.211,0.105) can be obtained and the luminescent brightness isabout 139%.

EXAMPLE 3

The light emitting device is made similar to Example 1 except that theraw materials of SrCO₃,MnCO₃ and Eu₂O₃ are adjusted and mixed accordingto the composition ratio of (Sr_(0.92),Eu_(0.05),Mn_(0.03))₂B₅O₉Cl bychanging the ratio in the phosphor of Example 1, thereby obtaining thecolor tone of the chromaticity coordinates (x,y)=(0.284,0.210) can beobtained. Moreover, the luminous efficiency is 24.7 lm/W at the drivecondition of 20 mA. If the luminescent brightness of comparative example1 is regarded as 100%, the luminescent brightness is about 213% in thelight emitting device excited by 400 nm according to Example 2. In thelight emitting device excited by 365 nm, the chromaticity coordinates(x,y)=(0.285,0.212) can be obtained and the luminescent brightness isabout 144%.

EXAMPLE 4

The light emitting device is made similar to Example 1 except that theraw materials of SrCO₃, MnCO₃ and Eu₂O₃ are adjusted and mixed accordingto the composition ratio of (Sr_(0.85),Eu_(0.05),Mn_(0.10))₂B₅O₉Cl bychanging the ratio in the phosphor of Example 1, thereby obtaining thecolor tone of the chromaticity coordinates (x,y)=(0.374,0.321).Moreover, the luminous efficiency is 26.1 lm/W at the drive condition of20 mA. If the luminescent brightness of comparative example 1 isregarded as 100%, the luminescent brightness is about 225% in the lightemitting device excited by 400 nm according to Example 4. In the lightemitting device excited by 365 nm, the chromaticity coordinates (xy)=(0.375 0.323) can be obtained and the luminescent brightness is about148%.

EXAMPLE 5

The light emitting device is made similar to Example 1 except that theraw materials of SrCO₃, MnCO₃ and Eu₂O₃ are adjusted and mixed accordingto the composition ratio of (Sr_(0.92),Eu_(0.03),Mn_(0.05))₂B₅O₉Cl bychanging the ratio in the phosphor of Example 1, thereby obtaining thecolor tone of the chromaticity coordinates (x,y)=(0.314,0.263).Moreover, luminous efficiency is 24.4 lm/W at the drive condition of 20mA. If the luminescent brightness of comparative example 1 is regardedas 100%, the luminescent brightness is about 210% in the light emittingdevice excited by 400 nm according to Example 5. In the light emittingdevice excited by 365 nm, the chromaticity coordinates (x,y)=(0.315,0.265) can be obtained and the luminescent brightness is about140%.

EXAMPLE 6

The light emitting device is made similar to Example 1 except that theraw materials of SrCO₃, MnCO₃ and Eu₂O₃ are adjusted and mixed accordingto the composition ratio of (Sr_(0.85),Eu_(0.10),Mn_(0.05))₂B₅O₉Cl bychanging the ratio in the phosphor of Example 1, thereby obtaining thecolor tone of which chromaticity coordinates (x,y)=(0.337, 0.278).Moreover, the luminous efficiency is 25.8 lm/W at the drive condition of20 mA. If the luminescent brightness of comparative example 1 isregarded as 100%, the luminescent brightness is about 222% in the lightemitting device of 400 nm excitation of Example 6. In the light emittingdevice excited by 365 nm, the chromaticity coordinates(x,y)=(0.338,0.280) can be obtained and the luminescent brightness isabout 150%.

EXAMPLE 7

The raw materials of CaCO₃, H₃BO₃, Eu₂O₃, MnCO₃ and NH₄Cl are weightedin the ratio according to the composition of(Ca_(0.90),Eu_(0.05),Mn_(0.05))₂B₅O₉Cl and mixed.

CaCO₃:180.1 g,

H₃BO₃: 309.1 g,

Eu₂O₃:17.6 g,

MnCO₃:11.5 g,

NH₄Cl:106.9 g,

The raw materials are weighed and fully mixed in the dry process by amixing machine such as a ball mil. The mixed raw materials are filled ina crucible of such as SiC, quartz or alumina and then the temperature israised to 1000° C. at the rate of 500° C./hour and maintained at theconstant temperature stage of 1000° C. for three hours in a reductionatmosphere of N₂, H₂. The fired product is wet crushed, dispersed,sieved, separated, washed, and dried, thereby obtaining the desiredphosphor powder.

The light emitting device of Example 7 is made similar to Example 1except that this phosphor is used, thereby obtaining the color tone ofthe chromaticity coordinates (x y)=(0.318, 0.247). Moreover, luminousefficiency is 23.5 lm/W at the drive condition of 20 mA. If theluminescent brightness of comparative example 1 is regarded as 100%, theluminescent brightness is about 202% in the light emitting deviceexcited by 400 nm according to Example 7. In the light emitting deviceexcited by 365 nm, the chromaticity coordinates (x,y)=(0.320,0.250) canbe obtained and the luminescent brightness is about 132%.

Although in this example CaCO₃ is used instead of SrCO₃ in Example 1 asa raw material of the phosphor, when MgCO₃ is used instead of SrCO₃ inExample 1 as a raw material, the phosphor of(Mg_(0.90)Eu_(0.05),Mn_(0.05))₂B₅O₉Cl can be obtained by the sameprocesses described above and can be used similarly in a light emittingdevice.

EXAMPLE 8

The light emitting device is made similar to Example 7 except that theraw materials of CaCO₃, MnCO₃ and Eu₂O₃ are adjusted and mixed accordingto the composition ratio of (Ca_(0.94),Eu_(0.05),Mn_(0.01))₂B₅O₉Cl bychanging the ratio in the phosphor of Example 7, thereby obtaining thecolor tone of the chromaticity coordinates (x,y)=(0.190,0.091).Moreover, luminous efficiency is 21.8 lm/W at the drive condition of 20mA. If the luminescent brightness of comparative example 1 is regardedas 100%, the luminescent brightness is about 188% in the light emittingdevice excited by 400 nm according to Example 8. In the light emittingdevice excited by 365 nm, the chromaticity coordinates (x, y)=(0.191,0.092) can be obtained and the luminescent brightness is about 124%.

EXAMPLE 9

The light emitting device is made similar to Example 7 except that theraw materials of CaCO₃, MnCO₃ and Eu₂O₃ are adjusted and mixed accordingto the composition ratio of (Ca_(0.92),Eu_(0.05),Mn_(0.03))₂B₅O₉Cl bychanging the ratio in the phosphor of Example 7, thereby obtaining thecolor tone of which chromaticity coordinates (x, y)=(0.263, 0.193).Moreover, the luminous efficiency is 22.9 lm/W at the drive condition of20 mA. If the luminescent brightness of comparative example 1 isregarded as 100%, the luminescent brightness is about 197% in the lightemitting device excited by 400 nm according to Example 9. In the lightemitting device of 365 nm excitation, the chromaticity coordinates (x,y)=(0.265, 0.195) can be obtained and the luminescent brightness isabout 139%.

EXAMPLE 10

The light emitting device is made similar to Example 7 except that theraw materials of CaCO₃, MnCO₃ and Eu₂O₃ are adjusted and mixed accordingto the composition ratio of (Ca_(0.85),Eu_(0.05),Mn_(0.10))₂B₅O₉Cl bychanging the ratio in the phosphor of Example 7, thereby obtaining thecolor tone of the chromaticity coordinates (x,y)=(0.352,0.300).Moreover, the luminous efficiency is 23.3 lm/W at the drive condition of20 mA. If the luminescent brightness of comparative example 1 isregarded as 100%, the luminescent brightness is about 201% in the lightemitting device excited by 400 nm according to Example 10. In the lightemitting device excited by 365 nm, the chromaticity coordinates (x,y)=(0.355, 0.302) can be obtained and the luminescent brightness isabout 133%.

EXAMPLE 11

The light emitting device is made similar to Example 7 except that theraw materials of CaCO₃, MnCO₃ and Eu₂O₃ are adjusted and mixed accordingto the composition ratio of (Ca_(0.92), Eu_(0.03),Mn_(0.05))₂B₅O₉Cl bychanging the ratio in the phosphor of Example 7, thereby obtaining thecolor tone of the chromaticity coordinates (x,y)=(0.293,0.241).Moreover, the luminous efficiency is 22.2 lm/W at the drive condition of20 mA. If the luminescent brightness of comparative example 1 isregarded as 100%, the luminescent brightness is about 191% in the lightemitting device excited by 400 nm according of Example 11. In the lightemitting device excited by 365 nm, the chromaticity coordinates (x,y)=(0.295, 0.243) can be obtained and the luminescent brightness is128%.

EXAMPLE 12

The light emitting device is made similar to Example 7 except that theraw materials of CaCO₃, MnCO₃ and Eu₂O₃ are adjusted and mixed accordingto the composition ratio of (Ca_(0.85),Eu_(0.10),Mn_(0.05))₂B₅O₉Cl bychanging the ratio in the phosphor of Example 7, thereby obtaining thecolor tone of chromaticity coordinates (x,y)=(0.326,0.252). Moreover,the luminous efficiency is 23.8 lm/W at the drive condition of 20 mA. Ifthe luminescent brightness of comparative example 1 is regarded as 100%,the luminescent brightness is about 205% in the light emitting deviceexcited by 400 nm of Example 12. In the light emitting device excited by365 nm, the chromaticity coordinates (x,y)=(0.328,0.255) can be obtainedand the luminescent brightness is about 136%.

EXAMPLE 13

The raw materials of BaCO₃, H₃BO₃, Eu₂O₃, MnCO₃ and NH₄Cl are weightedin the ratio according to (Ba_(0.90),Eu_(0.05),Mn_(0.05))₂B₅O₉Cl andmixed.

BaCO₃:355.2 g,

H₃BO₃:309.1 g,

Eu₂O₃:17.6 g,

MnCO₃:11.5 g,

NH₄Cl:106.9 g,

The raw materials are weighed and fully mixed in dry process by a mixingmachine such as a ball mil. The mixed raw materials are filled in acrucible of such as SiC, quartz or alumina and then the temperature israised to 900° C. at the rate of 500° C./hour and maintained at theconstant temperature stage of 900° C. for three hours in a reductionatmosphere of N₂, H₂. The fired product is wet crushed, dispersed,sieved, separated, washed and dried, thereby obtaining the desiredphosphor powder.

The light emitting device of Example 13 is made similar to Example 1except that this phosphor is used, thereby obtaining the color tone ofthe chromaticity coordinates (x,y)=(0.362,0.284). Moreover, the luminousefficiency is 16.8 lm/W at the drive condition of 20 mA. If theluminescent brightness of comparative example 1 is regarded as 100%, theluminescent brightness is about 145% in the light emitting deviceexcited by 400 nm according to Example 13. In the light emitting deviceof 365 nm excitation, the chromaticity coordinates (x,y)=(0.365,0.287)can be obtained and the luminescent brightness is about 95%.

EXAMPLE 14

The raw materials of SrCO₃, BaCO₃, CaCO₃, H₃BO₃, Eu₂O₃, MnCO₃ and NH₄Clare weighted in the ratio according to(Sr_(0.60),Ba_(0.10),Ca_(0.20),Eu_(0.05),Mn_(0.05))₂B₅O₉Cl and mixed.

SrCO₃: 177.1 g,

BaCO₃:39.5 g,

CaCO₃:40.4 g

H₃BO₃:309.1 g,

Eu₂O₃: 17.6 g,

MnCO₃:11.5 g,

NH₄Cl:106.9 g,

The raw materials are weighed and fully mixed by a mixing machine suchas a ball mil in the dry process. The mixed raw materials are filled ina crucible of such as SiC, quartz or alumina and then the temperature israised to 1000° C. at the rate of 500° C./hour and maintained at theconstant temperature stage of 1000° C. for three hours in a reductionatmosphere of N₂, H₂— The fired product is wet crushed, dispersed,sieved, separated, washed, and dried, thereby obtaining the phosphorpowder.

The light emitting device of Example 14 is made similar to Example 1except that this phosphor is used, thereby obtaining the color tone ofthe chromaticity coordinates (x,y)=(0.324,0.262). Moreover, the luminousefficiency is 24.3 lm/W at the drive condition of 20 mA. If theluminescent brightness of comparative example 1 is regarded as 100%, theluminescent brightness is about 209% in the light emitting deviceexcited by 400 nm according to Example 14. In the light emitting deviceexcited by 365 nm, the chromaticity coordinates (x,y)=(0.325,0.265) canbe obtained and the luminescent brightness is about 141%.

Although in this Example three elements of Sr, Ba and Ca are selected asM of (M_(1-x-y)Eu_(x)M′_(y))₂B₅O₉M′, the selection number and selectedelements are not restricted to these. That is to say, at least oneelement may be selected from the group of Mg, Ca, Ba and Sr. When anyelement is chosen, a light emitting device can be formed by a mannersimilar to this Example.

EXAMPLE 15

The light emitting device is made similar to Example 14 except that theraw materials of SrCO₃, MnCO₃ and Eu₂O₃ are adjusted and mixed accordingto the composition ratio of(Sr_(0.64),Ba_(0.10),Ca_(0.20),Eu_(0.05),Mn_(0.01))₂B₅O₉Cl by changingthe ratio in the phosphor of Example 14, thereby obtaining the colortone of chromaticity coordinates (x,y)=(0.203,0.097). Moreover, theluminous efficiency is 22.3 lm/W at the drive condition of 20 mA. If theluminescent brightness of comparative example 1 is regarded as 100%, theluminescent brightness is about 192% in the light emitting deviceexcited by 400 nm according to Example 15. In the light emitting deviceexcited by 365 nm, the chromaticity coordinates (x,y)=(0.204,0.098) canbe obtained and the luminescent brightness is about 134%.

EXAMPLE 16

The light emitting device is made similar to Example 14 except that theraw materials of SrCO₃, MnCO₃ and Eu₂O₃ are adjusted and mixed accordingto the composition ratio of(Sr_(0.62),Ba_(0.10),Ca_(0.20),Eu_(0.05),Mn_(0.03))₂B₅O₉Cl by changingthe ratio in the phosphor of Example 14, thereby obtaining the colortone of the chromaticity coordinates (x,y)=(0.276,0.201). Moreover, theluminous efficiency is 23.7 lm/W at the drive condition of 20 mA. If theluminescent brightness of comparative example 1 is regarded as 100%, theluminescent brightness is about 204% in the light emitting deviceexcited 400 nm according to Example 16. In the light emitting deviceexcited by 365 nm, the chromaticity coordinates (x,y)=(0.278,0.203) canbe obtained and the luminescent brightness is about 139%.

EXAMPLE 17

The light emitting device is made similar to Example 14 except that theraw materials of SrCO₃, MnCO₃ and Eu₂O₃ are adjusted and mixed accordingto the composition ratio of(Sr_(0.55),Ba_(0.10),Ca_(0.20),Eu_(0.05),Mn_(0.10))₂B₅O₉Cl by changingthe ratio in the phosphor of Example 14, thereby obtaining the colortone of which chromaticity coordinates (x,y)=(0.363,0.313). Moreover,the luminous efficiency is 25.2 lm/W at the drive condition of 20 mA. Ifthe luminescent brightness of comparative example 1 is regarded as 100%,the luminescent brightness is about 217% in the light emitting deviceexcited by 400 nm according to Example 17. In the light emitting deviceexcited by 365 nm, the chromaticity coordinates (x,y)=(0.365,0.316) canbe obtained and the luminescent brightness is about 143%.

EXAMPLE 18

The light emitting device is made similar to Example 14 except that theraw materials of SrCO₃, MnCO₃ and Eu₂O₃ are adjusted and mixed accordingto the composition ratio of(Sr_(0.62),Ba_(0.10),Ca_(0.20),Eu_(0.03),Mn_(0.05))₂B₅O₉Cl by changingthe ratio in the phosphor of Example 14, thereby the color tone of thechromaticity coordinates (x,y)=(0.317,0.256). Moreover, the luminousefficiency is 23.0 lm/W at the drive condition of 20 mA. If theluminescent brightness of comparative example 1 is regarded as 100%, theluminescent brightness is about 198% in the light emitting deviceexcited by 400 nm excitation according to Example 18. In the lightemitting device excited by 365 nm, the chromaticity coordinates(x,y)=(0.319,0.258) can be obtained and the luminescent brightness isabout 131%.

EXAMPLE 19

The light emitting device is made similar to Example 14 except that theraw materials of SrCO₃, MnCO₃ and Eu₂O₃ are adjusted and mixed accordingto the composition ratio of(Sr_(0.55),Ba_(0.10),Ca_(0.20),Eu_(0.10),Mn_(0.05))₂B₅O₉Cl by changingthe ratio in the phosphor of Example 14, thereby obtaining the colortone of the chromaticity coordinates (x,y)=(0.328,0.269). Moreover, theluminous efficiency is 25.0 lm/W at the drive condition of 20 mA. If theluminescent brightness of comparative example 1 is regarded as 100%, theluminescent brightness is about 215% in the light emitting deviceexcited by 400 nm according to Example 19. In the light emitting deviceexcited by 365 nm, the chromaticity coordinates (x,y)=(0.330,0.272) canbe obtained and the luminescent brightness is about 144%.

EXAMPLE 20

The light emitting device is made similar to Example 14 except that SnO₂is used as a raw material together with the raw materials of SrCO₃,BaCO₃, CaCO₃, H₃BO₃, Eu₂O₃, MnCO₃ and NH₄Cl and they are adjusted in theratio according to(Sr_(0.59),Ba_(0.10),Ca_(0.20),Eu_(0.05),Mn_(0.05),Sn_(0.01))₂B₅O₉Cl andmixed in the phosphor of Example 14, thereby obtaining the color tone ofthe chromaticity coordinates (x,y)=(0.322,0.261). Moreover, the luminousefficiency is 21.8 lm/W at the drive condition of 20 mA. If theluminescent brightness of comparative example 1 is regarded as 100%, theluminescent brightness is about 188% in the light emitting deviceexcited by 400 nm according Example 19. In the light emitting deviceexcited by 365 nm, the chromaticity coordinates (x y)=(0.324, 0.263) canbe obtained and the luminescent brightness is about 133%.

EXAMPLE 21

The light emitting device is made similar to Example 14 except thatFe₂O₃ is used as a raw material together with the raw materials ofSrCO₃, BaCO₃, CaCO₃, H₃BO₃, Eu₂O₃, MnCO₃ and NH₄Cl and they are adjustedin the ratio according to(Sr_(0.59),Ba_(0.10),Ca_(0.20),Eu_(0.05),Mn_(0.05),Fe_(0.01))₂B₅O₉Cl andmixed in the Example 14, thereby obtaining the color tone of thechromaticity coordinates (x,y)=(0.342,0.281). Moreover, the luminousefficiency is 21.9 lm/W at the drive condition of 20 mA. If theluminescent brightness of comparative example 1 is regarded as 100%, theluminescent brightness is about 189% in the light emitting deviceexcited by 400 nm according to Example 19. In the light emitting deviceexcited by 365 nm, the chromaticity coordinates (x,y)=(0.345,0.285) canbe obtained and the luminescent brightness is about 121%.

EXAMPLE 22

The light emitting device is made similar to Example 14 except thatCr₂O₃ is used as a raw material together with the raw materials ofSrCO₃, BaCO₃, CaCO₃, H₃BO₃, Eu₂O₃, MnCO₃ and NH₄Cl and they are adjustedin the ratio according to(Sr_(0.59),Ba_(0.10),Ca_(0.20),Eu_(0.05),Mn_(0.05),Cr_(0.01))₂B₅O₉Cl andmixed in the Example 14, thereby obtaining the color tone of thechromaticity coordinates (x,y)=(0.343,0.278). Moreover, the luminousefficiency is 22.3 lm/W at the drive condition of 20 mA. If theluminescent brightness of comparative example 1 is regarded as 100%, theluminescent brightness is about 192% in the light emitting deviceexcited by 400 nm according to Example 19. In the light emitting deviceexcited by 365 nm, the chromaticity coordinates (x,y)=(0.345,0.280) canbe obtained and the luminescent brightness is about 125%.

EXAMPLE 23

The light emitting device is made similar to the device of Example 1except that all of the raw material of NH₄Cl is replaced by NH₄Br andthe raw materials are adjusted in the ratio according to(Sr_(0.90),Eu_(0.05),Mn_(0.05))₂B₅O₉Br and mixed in the phosphor of theExample 1, thereby obtaining the color tone of the chromaticitycoordinates (x,y)=(0.344,0.291). Moreover, the luminous efficiency is27.4 lm/W at the drive condition of 20 mA. If the luminescent brightnessof comparative example 1 is regarded as 100%, the luminescent brightnessis about 236% in the light emitting device excited by 400 nm accordingto Example 23. In the light emitting device excited by 365 nm, thechromaticity coordinates (x,y)=(0.345,0.293) can be obtained and theluminescent brightness is about 155%.

Although NH4Br is used as a raw material instead of NH4Cl in thisexample, NH₄F or NH₄I may be used as a raw material to be replaced.

EXAMPLE 24

The light emitting device is made similar to the device of Example 1except that a half of the raw material of NH₄Cl is replaced by NH₄F andthe raw materials are adjusted in the ratio according to(Sr_(0.90),Eu_(0.05),Mn_(0.05))₂B₅O₉Cl_(0.5)F_(0.5) and mixed in thephosphor of the Example 1, thereby obtaining the color tone of whichchromaticity coordinates (x,y) is (0.313,0.255). Moreover, the luminousefficiency is 23.3 lm/W at the drive condition of 20 mA. If theluminescent brightness of comparative example 1 is regarded as 100%, theluminescent brightness is about 201% in the light emitting deviceexcited by 400 nm according to Example 23. In the light emitting deviceexcited by 365 nm, the chromaticity coordinates (x,y)=(0.315,0.257) canbe obtained and the luminescent brightness is about 138%.

EXAMPLE 25

The light emitting device is made similar to the device of Example 1except that a half of the raw material of NH₄Cl is replaced by NH₄I andthe raw materials are adjusted in the ratio according to(Sr_(0.90),Eu_(0.05),Mn_(0.05))₂B₅O₉Cl_(0.5)I_(0.5) and mixed in thephosphor of the Example 1, thereby obtaining the color tone of whichchromaticity coordinates (x,y) is (0.327,0.270) is obtained. Moreover,the luminous efficiency is 20.7 lm/W at the drive condition of 20 mA. Ifthe luminescent brightness of comparative example 1 is regarded as 100%,the luminescent brightness is about 178% in the light emitting deviceexcited by 400 nm according to Example 25. In the light emitting deviceexcited by 365 nm, the chromaticity coordinates (x,y)=(0.329,0.271) canbe obtained and the luminescent brightness is about 120%.

EXAMPLE 26

The light emitting device is made similar to the device of Example 1except that a part of the raw material of NH₄Cl is replaced by NH₄Br andNH₄F, and the raw materials are adjusted in the ratio according to(Sr_(0.90),Eu_(0.05),Mn_(0.05))₂B₅O₉Cl_(0.4)Br_(0.3)F_(0.3) and mixed inthe phosphor of the Example 1, thereby obtaining the color tone of thechromaticity coordinates (x,y)=(0.326,0.266). Moreover, the luminousefficiency is 24.9 lm/W at the drive condition of 20 mA. If theluminescent brightness of comparative example 1 is regarded as 100%, theluminescent brightness is about 214% in the light emitting deviceexcited by 400 nm according to Example 26. In the light emitting deviceexcited by 365 nm, the chromaticity coordinates (x,y)=(0.328,0.268) canbe obtained and the luminescent brightness is about 144%.

EXAMPLE 27

The light emitting device is made similar to the device of Example 7except that all of the raw material of NH₄Cl is replaced by NH₄Br andthe raw materials are adjusted in the ratio according to(Ca_(0.90),Eu_(0.05),Mn_(0.05))₂B₅O₉Br and mixed in the phosphor of theExample 7, thereby obtaining the color tone of the chromaticitycoordinates (x,y)=(0.337,0.285). Moreover, the luminous efficiency is258 lm/W at the drive condition of 20 mA. If the luminescent brightnessof comparative example 1 is regarded as 100%, the luminescent brightnessis about 222% in the light emitting device of 400 nm excitation ofExample 27. In the light emitting device excited by 365 nm, thechromaticity coordinates (x,y)=(0.339,0.287) can be obtained and theluminescent brightness is about 147%.

EXAMPLE 28

The light emitting device is made similar to the device of Example 7except that a half of the raw material of NH₄Cl is replaced by NH₄F andthe raw materials are adjusted in the ratio according to(Ca_(0.90),Eu_(0.05),Mn_(0.05))₂B₅O₉Cl_(0.5)F_(0.5) and mixed in thephosphor of the Example 7, thereby obtaining the color tone of whichchromaticity coordinates (x,y)=(0.308,0.250). Moreover, the luminousefficiency is 22.1 lm/W at the drive condition of 20 mA. If theluminescent brightness of comparative example 1 is regarded as 100%, theluminescent brightness is about 130% in the light emitting deviceexcited by 400 nm according to Example 28. In the light emitting deviceexcited by 365 nm, the chromaticity coordinates (x,y)=(0.310,0.252) canbe obtained and the luminescent brightness is about 190%.

EXAMPLE 29

The light emitting device is made similar to the device of Example 7except that a half of the raw material of NH₄Cl is replaced by NH₄I andthe raw materials are adjusted in the ratio according to(Ca_(0.90),Eu_(0.05),Mn_(0.05))₂B₅O₉Cl_(0.5)I_(0.5) and mixed in thephosphor of the Example 7, thereby obtaining the color tone of thechromaticity coordinates (x,y)=(0.321,0.264). Moreover, the luminousefficiency is 19.4 lm/W at the drive condition of 20 mA. If theluminescent brightness of comparative example 1 is regarded as 100%, theluminescent brightness is about 167% in the light emitting deviceexcited by 400 nm according to Example 29. In the light emitting deviceexcited by 365 nm, the chromaticity coordinates (x,y)=(0.324,0.266) canbe obtained and the luminescent brightness is about 112%.

EXAMPLE 30

The light emitting device is made similar to the device of Example 7except that a part of the raw material of NH₄Cl is replaced by NH₄Br andNH₄F, and the raw materials are adjusted in the ratio according to(Ca_(0.90),Eu_(0.05),Mn_(0.05))₂B₅O₉Cl_(0.4)Br_(0.3)F_(0.3) and mixed inthe phosphor of the Example 7, thereby obtaining the color tone of whichchromaticity coordinates (x,y)=(0.321,0.260) is obtained. Moreover, theluminous efficiency is 23.8 lm/W at the drive condition of 20 mA. If theluminescent brightness of comparative example 1 is regarded as 100%, theluminescent brightness is about 205% in the light emitting deviceexcited by 400 nm according to Example 30. In the light emitting deviceexcited by 365 nm, the chromaticity coordinates (x,y)=(0.323,0.263) canbe obtained and the luminescent brightness is about 136%.

EXAMPLE 31

The light emitting device is made similar to the device of Example 14except that all of the raw material of NH₄Cl is replaced by NH₄Br andthe raw materials are adjusted in the ratio according to(Sr_(0.60),Ba_(0.10),Ca_(0.20),Eu_(0.05),Mn_(0.05))₂B₅O₉Br and mixed inthe phosphor of the Example 14, thereby obtaining the color tone of thechromaticity coordinates (x,y)=(0.338,0.286). Moreover, the luminousefficiency is 24.6 lm/W at the drive condition of 20 mA. If theluminescent brightness of comparative example 1 is regarded as 100%, theluminescent brightness is about 227% in the light emitting deviceexcited by 400 nm according to Example 31. In the light emitting deviceexcited by 365 nm, the chromaticity coordinates (x,y)=(0.340,0.288) canbe obtained and the luminescent brightness is about 149%.

EXAMPLE 32

The light emitting device is made similar to the device of Example 14except that a half of the raw material of NH₄Cl is replaced by NH₄F andthe raw materials are adjusted in the ratio according to(Sr_(0.60),Ba_(0.10),Ca_(0.20),Eu_(0.05),Mn_(0.05))₂B₅O₉Cl_(0.5)F_(0.5)and mixed in the phosphor of the Example 14, thereby obtaining the colortone of the chromaticity coordinates (x,y)=(0.310,0.249). Moreover, theluminous efficiency is 22.9 lm/W at the drive condition of 20 mA. If theluminescent brightness of comparative example 1 is regarded as 100%, theluminescent brightness is about 197% in the light emitting deviceexcited by 400 nm according to Example 32. In the light emitting deviceexcited by 365 nm, the chromaticity coordinates (x,y)=(0.340,0.288) canbe obtained and the luminescent brightness is about 133%.

EXAMPLE 33

The light emitting device is made similar to the device of Example 14except that a half of the raw material of NH₄Cl is replaced by NH₄I andthe raw materials are adjusted in the ratio according to(Sr_(0.60),Ba_(0.10),Ca_(0.20),Eu_(0.05),Mn_(0.05))₂B₅O₉Cl_(0.5)I_(0.5)and mixed in the phosphor of the Example 14, thereby obtaining the colortone of which chromaticity coordinates (x,y)=(0.320,0.264). Moreover,the luminous efficiency is 19.9 lm/W at the drive condition of 20 mA. Ifthe luminescent brightness of comparative example 1 is regarded as 100%,the luminescent brightness is about 171% in the light emitting deviceexcited by 400 nm according to Example 33. In the light emitting deviceexcited by 365 nm, the chromaticity coordinates (x,y)=(0.322,0.266) canbe obtained and the luminescent brightness is about 116%.

EXAMPLE 34

The light emitting device is made similar to the device of Example 14except that a part of the raw material of NH₄Cl is replaced by NH₄Br andNH₄F, and the raw materials are adjusted in the ratio according to(Sr_(0.60),Ba_(0.10),Ca_(0.20),Eu_(0.05),Mn_(0.05))₂B₅O₉Cl_(0.4)Br_(0.3)F_(0.3)and mixed in the phosphor of the Example 14, thereby obtaining the colortone of which chromaticity coordinates (x,y)=(0.320,0.262). Moreover,the luminous efficiency is 24.3 lm/W at the drive condition of 20 mA. Ifthe luminescent brightness of comparative example 1 is regarded as 100%,the luminescent brightness is about 209% in the light emitting deviceexcited by 400 nm according to Example 34. In the light emitting deviceexcited by 365 nm, the chromaticity coordinates (x,y)=(0.322, 0.264) canbe obtained and the luminescent brightness is about 139%.

Although in this Example the phosphor in which three elements of Cl, Brand F are selected as M″ in the general formula of(M_(1-x-y)Eu_(x)M′_(y))₂B₅O₉M″ is used, the selection number and thekinds of selected elements are not restricted to these as long as atleast one kind is selected from halogen. When any element is selected, alight emitting device can be formed by the similar method as thisExample.

EXAMPLE 35

The light emitting device is made similar to the device of Example 1except that the color conversion layer is formed by the coating mediumdispersively mixed with the phosphor of(Sr_(0.90),Eu_(0.05),Mn_(0.05))₂B₅O₉Cl and the phosphor of SrAl₂O₄:Euwhich is a second phosphor capable of emitting a green light excited bythe excitation light of the LED chip 1, thereby obtaining the color toneof the chromaticity coordinates (x,y)=(0.325,0.333). Moreover, theluminous efficiency is 32.1 lm/W at the drive condition of 20 mA. If theluminescent brightness of comparative example 1 is regarded as 100%, theluminescent brightness is about 242% in the light emitting deviceexcited by 400 nm according to Example 35. In the light emitting deviceexcited by 365 nm, the chromaticity coordinates (x,y)=(0.323,0.335) canbe obtained and the luminescent brightness is about 162%.

EXAMPLE 36

The light emitting device is made similar to the device of Example 4except that the color conversion layer is formed by the coating mediumdispersively mixed with the phosphor of(Sr_(0.85),Eu_(0.05),Mn_(0.10))₂B₅O₉Cl and the phosphor of Sr₄Al₁₄O₂₅:Euwhich is capable of emitting a blue green light excited by theexcitation light of the LED chip 1 in Example 4, thereby obtaining thecolor tone of the chromaticity coordinates (x,y)=(0.324,0.330).Moreover, the luminous efficiency is 30.8 lm/W at the drive condition of20 mA. If the luminescent brightness of comparative example 1 isregarded as 100%, the luminescent brightness is about 255% in the lightemitting device excited by 400 nm according to Example 36. In the lightemitting device excited by 365 nm, the chromaticity coordinates(x,y)=(0.328,0.333) can be obtained and the luminescent brightness isabout 171%.

EXAMPLE 37

The light emitting device is made similar to the device of Example 7except that the color conversion layer is formed by the coating mediumdispersively mixed with the phosphor of(Ca_(0.90),Eu_(0.05),Mn_(0.05))₂B₅O₉Cl and the phosphor of SrAl₂O₄:Euwhich is capable of emitting a green light excited by the excitationlight of the LED chip 1 in Example 7, thereby obtaining the color toneof the chromaticity coordinates (x,y)=(0.320,0.327). Moreover, theluminous efficiency is 31.1 lm/W at the drive condition of 20 mA. If theluminescent brightness of comparative example 1 is regarded as 100%, theluminescent brightness is about 240% in the light emitting deviceexcited by 400 nm according to Example 37. In the light emitting deviceexcited by 365 nm, the chromaticity coordinates (x,y)=(0.318,0.330) canbe obtained and the luminescent brightness is about 158%.

EXAMPLE 38

The light emitting device is made similar to the device of Example 10except that the color conversion layer is formed by the coating mediumdispersively mixed with the phosphor of(Ca_(0.85),Eu_(0.05),Mn_(0.10))₂B₅O₉Cl and the phosphor of Sr₄Al₁₄O₂₅:Euwhich is capable of emitting a blue green light excited by theexcitation light of the LED chip 1 in Example 10, thereby obtaining thecolor tone of chromaticity coordinates (x,y)=(0.324,0.328). Moreover,the luminous efficiency is 29.8 lm/W at the drive condition of 20 mA. Ifthe luminescent brightness of comparative example 1 is regarded as 100%,the luminescent brightness is about 239% in the light emitting device of400 nm excitation of Example 38. In the light emitting device of 365 nmexcitation, the chromaticity coordinates (x,y)=(0.324,0.329) can beobtained and the luminescent brightness is about 160%.

EXAMPLE 39

The light emitting device is made similar to the device of Example 14except that the color conversion layer is formed by the coating mediumdispersively mixed with the phosphor of(Sr_(0.06),Ba_(0.10),Ca_(0.20),Eu_(0.05),Mn_(0.10))₂B₅O₉Cl and thephosphor of SrAl₂O₄:Eu which is a second phosphor capable of emitting agreen light excited by the excitation light of the LED chip 1 in Example14, thereby obtaining the color tone of the chromaticity coordinates(x,y)=(0.320,0.327). Moreover, the luminous efficiency is 35.5 lm/W atthe drive condition of 20 mA. If the luminescent brightness ofcomparative example 1 is regarded as 100%, the luminescent brightness isabout 259% in the light emitting device excited by 400 nm excitationaccording to Example 39. In the light emitting device excited by 365 nm,the chromaticity coordinates (x,y)=(0.320,0.328) can be obtained and theluminescent brightness is about 169%.

EXAMPLE 40

The light emitting device is made similar to the device of Example 17except that the color conversion layer is formed by the coating mediumdispersively mixed with the phosphor of (Sr_(0.55),Ba_(0.10),Ca_(0.20),Eu_(0.05),Mn_(0.10))₂B₅O₉Cl and the phosphor of Sr₄Al₁₄O₂₅:Euwhich is a second phosphor capable of emitting a blue green lightexcited by the excitation light of the LED chip 1 in the Example 17,thereby obtaining the color tone of the chromaticity coordinates(x,y)=(0.319,0.330). Moreover, the luminous efficiency is 30.8 lm/W atthe drive condition of 20 mA. If the luminescent brightness ofcomparative example 1 is regarded as 100%, the luminescent brightness isabout 256% in the light emitting device excited by 400 nm according toExample 40. In the light emitting device excited by 365 nm, thechromaticity coordinates (x,y)=(0.320,0.333) can be obtained and theluminescent brightness is about 167%.

EXAMPLE 41

The light emitting device is made similar to the device of Example 8except that the color conversion layer is formed by the coating mediumdispersively mixed with the phosphor of(Ca_(0.94),Eu_(0.05),Mn_(0.01))₂B₅O₉Cl and the phosphor of(Y_(0.8)Gd_(0.2))₃Al₅O₁₂:Ce which is a second phosphor capable ofemitting a yellow light excited by the light emitted from the firstphosphor in Example 8, thereby obtaining the color tone of thechromaticity coordinates (x,y)=(0.325,0.334). Moreover, the luminousefficiency is 25.8 lm/W at the drive condition of 20 mA. Although, thelight emitting device is constituted by adding the second phosphor tothe light emitting device of example 8 in this example, the lightemitting device of any one of examples 1-40 may include the secondphosphor in the color conversion layer in the similar way.

EXAMPLE 42

The light emitting device is made similar to the device of Example 41except that the phosphor of (Ca_(0.64),Ba_(0.10),Sr_(0.20), Eu_(0.05),Mn_(0.01))₂B₅O₉Cl is used as a first phosphor in Example 41, therebyobtaining the color tone of the chromaticity coordinates(x,y)=(0.323,0.338). Moreover, the luminous efficiency is 25.7 lm/W atthe drive condition of 20 mA.

EXAMPLE 43

The light emitting device is made similar to the device of Example 41except that the phosphor of(Ca_(0.64),Ba_(0.10),Sr_(0.20),Eu_(0.50),Sn_(0.01))₂B₅O₉Cl is used as afirst phosphor in Example 41, thereby obtaining the color tone of whichchromaticity coordinates (x,y)=(0.323, 0.338) is obtained. Moreover, theluminous efficiency is 23.5 lm/W at the drive condition of 20 mA.

EXAMPLE 44

The light emitting device is made similar to the device of Example 41except that the phosphor of(Ca_(0.64),Ba_(0.10),Sr_(0.20),Eu_(0.50),Fe_(0.01))₂B₅O₉Cl is used as afirst phosphor in Example 41, thereby obtaining the color tone of whichchromaticity coordinates (x,y)=(0.322,0.333). Moreover, the luminousefficiency is 24.8 lm/W at the drive condition of 20 mA.

EXAMPLE 45

The light emitting device is made similar to the device of Example 41except that the phosphor of(Ca_(0.64),Ba_(0.10),Sr_(0.20),Eu_(0.50),Cr_(0.01))₂B₅O₉Cl is used as afirst phosphor in Example 41, thereby obtaining the color tone of whichchromaticity coordinates (x,y)=(0.324,0.335) is obtained. Moreover, theluminous efficiency is 23.9 lm/W at the drive condition of 20 mA.

INDUSTRIAL APPLICABILITY

The present invention makes it possible to produce the light emittingdevice having a high brightness and a good color rendering property witha good process yield, making good use of advantages of a semiconductorlight emitting element. With this, it can be used as a light source suchas a lighting apparatus of a medical application, and the flash plate ofa copying machine, in which the good color rendering properties arerequired. Since the phosphor of the present invention has the excitationspectrum having a wide half band width and a nearly flat portion in thevicinity of the wavelength in which relative luminous efficiency ishigh, the color shading generated by the dispersion of the emissionspectra of the light emitting elements is improved. Moreover, thepresent invention makes it possible to produce a light emitting elementwith a good productivity due to its relatively simple structure. Thelight emitting device having a good color rendering property, in whichthe component of long wavelength is taken out comparatively easily, canbe obtained. The light emitting device capable of emitting a whitelight, emitting a desired neutral color with high brightness, andadjusting a delicate color tone, can be obtained.

1. A light emitting device comprising: a semiconductor light emitting element; and a phosphor which for converting a part of a luminescence spectrum emitted from said semiconductor light emitting element, wherein: the luminescence spectrum of said semiconductor light emitting element is located between a near ultraviolet region and a short-wavelength visible region; said semiconductor light emitting element has a main peak in a range from 360 nm to 400 nm; and said phosphor is represented by a general formula of (M_(1-x-y)Eu_(x)M′_(y))₂B₅O₉M″, where M is at least one selected from the group consisting of Mg, Ca, Ba, and Sr, M′ is at least one selected from the group consisting of Mn, Fe, Cr, Sn, 0.0001≦x≦0.5, and 0.00011≦y≦0.5, and M″ is at least one halogen selected from the group consisting of F, Cl, Br, and I.
 2. The light emitting element according to claim 1, wherein a light emitting layer of said semiconductor light emitting element is made of a nitride semiconductor including at least In and Ga.
 3. The light emitting element according to claim 1; wherein a light emitting layer of said semiconductor light emitting element is made of a nitride semiconductor including at least Ga and Al.
 4. The light emitting element according to claim 1, wherein said phosphor is an alkaline earth metal boric halide phosphor activated by at least Mn and Eu.
 5. The light emitting device according to claim 1, further comprising a phosphor selected from the group consisting of: an alkaline earth halogen apatite phosphor activated by Eu, or Eu and Mn, wherein said alkaline earth halogen apatite phosphor is selected from the group consisting of (Sr)₅(PO₄)₃(Sr)₅(PO₄)₃(Cl), (Sr)₅(PO₄)₃(Br), (Sr)₅(PO₄)₃(I), (Ca)₅(PO₄)₃(F), (Ca)₅(PO₄)₃(Cl), (Ca)₅(PO₄)₃(Br), (Ca)₅(PO₄)(I), (Ba)₅(PO₄)₃(F), (Ba)₅(PO₄)₃(Cl), (Ba)₅(PO₄)₃(Br), (Ba)₅(PO₄)₃(I), (Mg)₅(PO₄)₃(F), (Mg)₅(PO₄)₃(Cl), (Mg)₅(PO₄)₃(Br), (Mg)₅(PO₄)₃(I), (Zn)₅(PO₄)₃(F), (Zn)₅(PO₄)₃(Cl), (Zn)₅(PO₄)₃(Br), and (Zn)₅(PO₄)₃(I); an alkaline earth metal aluminate phosphor selected from the group consisting of SrAl₂O₄:Eu, Sr₄Al₁₄O₂₅:Eu(Mn), CaAl₂O₄:Eu(Mn), BaMg₂Al₁₆O₂₇:Eu, BaMg₂Al₁₆O₁₂:Eu,Mn, BaMgAl₁₀O₁₇:Eu(Mn); a phosphor of CaO—Al₂O₃—SiO₂ including nitride activated by one of Eu and Cr [oxynitride fluoroglass]; a phosphor of M_(x)Si_(y)N_(z):Eu where M is at least one selected from the group consisting of Mg, Ca, Ba, Sr, Zn, and z=⅔x+ 4/3y); an yttrium aluminate phosphor activated by cerium; a rare earth acid sulfide phosphor activated by Eu, wherein said rare earth acid sulfide phosphor is selected from the group consisting of La₂O₂S, Y₂O₂S and Gd₂O₂S); and an organic complex phosphor activated by one of Eu, Cu, and Mn, wherein said organic complex phosphor is selected from the group consisting of (Sr)₅(PO₄)₃Cl:Eu, (Ca)₅(PO₄)₃Cl:Eu, (Ba)₅(PO₄)₃Cl:Eu, (Mg)₅(PO₄)₃Cl:Eu, ZnS:Cu, Zn₂GeO₄:Mn, (Sr)Ga₂S₄:Eu, (Ca)Ga₂S₄:Eu, (Ba)Ga₂S₄:Eu, (Mg)Ga₂S₄:Eu, (Sr)₂Si₅N:Eu, (Ca)₂Si₅N:Eu, (Ba)₂Si₅N:Eu, and (Mg)₂Si₅N:Eu. 